What does the output of a printed character array mean?

问题

I'm moving from C to Java now and I was following some tutorials regarding Strings. At one point in the tutorials they showed instantiating a new string from a character array then printing the string. I was following along, but I wanted to print both the character array and the string so I tried this:

class Whatever {
    public static void main(String args[]) {
        char[] hello = { 'h', 'e', 'l', 'l', 'o', '.'};
        String hello_str = new String(hello);
        System.out.println(hello + " " + hello_str);
    }
}

My output was something like this:

[C@9304b1 hello.

Clearly, this is not how you would print a character array in Java. However I'm wondering if I just got garbage? I read on some site that printing a character array give you an address, but that doesn't look like an address to me... I haven't found a lot online about it.

So, what did I just print?
and bonus questions: How do you correctly print a character array in java?

回答1:

However I'm wondering if I just got garbage?

No, you got the result of Object.toString(), which isn't overridden in arrays:

The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:
getClass().getName() + '@' + Integer.toHexString(hashCode())

So it's not garbage, in that it has a meaning... but it's not a particularly useful value, either.

And your bonus question...

How do you correctly print a character array in java?

Call Arrays.toString(char[]) to convert it to a string... or just

System.out.println(hello);

which will call println(char[]) instead, which converts it into a string. Note that Arrays.toString will build a string which is obviously an array of characters, whereas System.out.println(hello) is broadly equivalent to System.out.println(new String(hello))

来源：https://stackoverflow.com/questions/13764700/what-does-the-output-of-a-printed-character-array-mean

标签

java

string

character-arrays